com.power4j.fist.boot.mybaits.util.LambdaHelper Maven / Gradle / Ivy
/*
* Copyright 2021 ChenJun ([email protected] & https://github.com/John-Chan)
*
* Licensed under the GNU LESSER GENERAL PUBLIC LICENSE 3.0;
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.gnu.org/licenses/lgpl.html
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.power4j.fist.boot.mybaits.util;
import com.baomidou.mybatisplus.core.metadata.TableInfo;
import com.baomidou.mybatisplus.core.metadata.TableInfoHelper;
import com.baomidou.mybatisplus.core.toolkit.Assert;
import com.baomidou.mybatisplus.core.toolkit.LambdaUtils;
import com.baomidou.mybatisplus.core.toolkit.support.ColumnCache;
import com.baomidou.mybatisplus.core.toolkit.support.LambdaMeta;
import com.baomidou.mybatisplus.core.toolkit.support.SFunction;
import org.apache.ibatis.reflection.property.PropertyNamer;
import java.util.Map;
import java.util.Optional;
/**
* @author CJ ([email protected])
* @date 2021/10/13
* @since 1.0
*/
public class LambdaHelper {
private final Class entityClass;
private Map columnMap = null;
private boolean initColumnMap = false;
public LambdaHelper(Class entityClass) {
this.entityClass = entityClass;
}
public Class getEntityClass() {
return entityClass;
}
/**
* 实体类信息
* @return TableInfo
*/
public Optional getTableInfo() {
return Optional.ofNullable(TableInfoHelper.getTableInfo(entityClass));
}
/**
* 获取列名
* @param colFunc 字段求值函数,比如 {@code User::getName}
* @param onlyColumn 是否只包含列名称
* @return 列名称
*/
public String colToStr(SFunction colFunc, boolean onlyColumn) {
return getColumn(LambdaUtils.extract(colFunc), onlyColumn);
}
/**
* 获取 SerializedLambda 对应的列信息，从 lambda 表达式中推测实体类
* @param lambda lambda 表达式
* @param onlyColumn 是否只包含列名称
* @return 列
*/
protected String getColumn(LambdaMeta lambda, boolean onlyColumn) {
Class aClass = lambda.getInstantiatedClass();
tryInitCache(aClass);
String fieldName = PropertyNamer.methodToProperty(lambda.getImplMethodName());
ColumnCache columnCache = getColumnCache(fieldName, aClass);
return onlyColumn ? columnCache.getColumn() : columnCache.getColumnSelect();
}
private void tryInitCache(Class lambdaClass) {
synchronized (this) {
if (!initColumnMap) {
final Class entityClass = getEntityClass();
if (entityClass != null) {
lambdaClass = entityClass;
}
columnMap = LambdaUtils.getColumnMap(lambdaClass);
initColumnMap = true;
}
}
Assert.notNull(columnMap, "can not find lambda cache for this entity [%s]", lambdaClass.getName());
}
private ColumnCache getColumnCache(String fieldName, Class lambdaClass) {
ColumnCache columnCache = columnMap.get(LambdaUtils.formatKey(fieldName));
Assert.notNull(columnCache, "can not find lambda cache for this property [%s] of entity [%s]", fieldName,
lambdaClass.getName());
return columnCache;
}
}